Pilby's U.S. Pat. No. 5,556,186 issued in 1994 was a pioneer invention that changed the way diffused light is controlled by photographers and cinematographers. Prior to Pilby's invention, diffused light for photographer's soft boxes or other soft light sources was controlled by bulky “barn doors” attached around the soft sources, or “flags,” typically large black cloths in a wire frame mounted on stands or hung overhead near light sources. Light control grids that existed were rigid, heavy, bulky and expensive. Pilby's Lightools® Soft Egg Crates® Light Control Grids changed all that. The grids are a flexible fabric material and thus collapsible, but of a construction with intersecting and interlocking strips keeping the grid taut, and easy to manufacture. The invention met with critical acclaim and much commercial success the past 15 years. Over that time period the '186 patent claims were also successfully enforced a number of times, indicating the industry's acceptance and respect for the patent.
A standard photographic setup using the light control grid as per the '186 patent is shown in FIG. 1. Photographers often desire a soft light condition that is best achieved by: (1) using a dimensionally large light source to create soft light and (2) placing the photographic subject relatively close to the light source. The large light source 20 is a diffused light source with a square aperture forming a reflective enclosure around the lamp. The optimal position of the subject 22 to obtain a maximum soft light benefit is a distance approximately no greater than the diagonal dimension of the light source aperture (D), but this close subject position has a drawback. With Pilby's light control grids 26 of the '186 patent applied to the aperture 30, small subjects closer than about three (3) times the diagonal dimension receive less of the full large soft light capability, because much of the light headed for the subject 22 is blocked by neighboring cells of the grid. Even though the '186 light control grid 26 quite effectively prevents light spillage overall, at close proximity light is not optimally controlled, an undesirable effect that photographer's have now had a long interest in mitigating.
How light can be blocked at close range is seen from the point of view of the photographic subject 22, as shown in FIGS. 2A-D. The '186 light control grid 26 has a large rectangular frame 32 with intersecting and interlocking fabric strips 34 that form a large number of light channels 36, which are each several inches long (the width of the strips 34) and pointed straight out from the light source 20 and oriented parallel to one another. When viewed by the subject 22 from a distance that is closer than about three times the diagonal dimension of the grid 26, the light coming through the outermost light channels 36 is occluded from subject's view by the walls of the light channels 36.
The magnitude of the occlusive effect can be seen when comparing FIG. 2A to FIG. 2C, where the prior art light control grid 26 is again shown in one-point perspective from the viewpoint of the subject 22 located front-center of the light source 20. In FIG. 2A, the subject 22 is a distance X1 from the light control grid 26, where X1=1D (one times the diagonal dimension of the light source). The light channels 36 located near the center of the grid 26 are not occluded since the subject 22 is directly in front of these light channels 36. The light channels 36 located near the outermost portion of the grid 26, approaching the frame 32 and especially at the corners, are partially occluded from view by the fabric strips 34 that form the walls of the light channels 36. FIG. 2B shows section 2B-2B of FIG. 2A, where the parallel relationship of the prior art fabric strips 34 can be clearly seen, which form the light channels 36 that direct the light 38 straight forward, some portion of the light 22 not being directed at the subject.
This occlusive effect is further accentuated in FIG. 2C where the subject 22 is moved an even shorter distance X2, where X2=0.5D (one-half diagonal dimension). The light channels 36 near the central area are again not occluded. The light channels 36 near the outer regions of the grid 26, however, are substantially occluded by the fabric strips 34 of the light channel 36 walls, disadvantageously blocking a good portion of the light 38 from reaching the subject 22. For the popular prior art Soft Egg Crates® Grids currently being sold, only these centermost light channels cast light directly on the subject 22. At close distances this may mean that as little as 10% of the available light is directly cast on the subject, creating less than ideal lighting conditions. This significant issue has been unresolved in the photography/cinematography circles since the '186 patent issued and the commercial embodiment went on sale about 15 years ago.
Accordingly, there exists a continued need for a significantly improved light control grid for photography close to large light source, that overcomes the limitations of Pilby's earlier invention and the other prior art, and is again embodied in a simple and inexpensive device, that is easy to use and conveniently stored when not in use.